| |
| /*--------------------------------------------------------------------*/ |
| /*--- Semaphore stuff. sema.c ---*/ |
| /*--------------------------------------------------------------------*/ |
| |
| /* |
| This file is part of Valgrind, a dynamic binary instrumentation |
| framework. |
| |
| Copyright (C) 2000-2012 Julian Seward |
| jseward@acm.org |
| |
| This program is free software; you can redistribute it and/or |
| modify it under the terms of the GNU General Public License as |
| published by the Free Software Foundation; either version 2 of the |
| License, or (at your option) any later version. |
| |
| This program is distributed in the hope that it will be useful, but |
| WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| General Public License for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with this program; if not, write to the Free Software |
| Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA |
| 02111-1307, USA. |
| |
| The GNU General Public License is contained in the file COPYING. |
| */ |
| |
| #include "pub_core_basics.h" |
| #include "pub_core_debuglog.h" |
| #include "pub_core_vki.h" |
| #include "pub_core_libcassert.h" |
| #include "pub_core_libcfile.h" |
| #include "pub_core_libcproc.h" // For VG_(gettid)() |
| #include "pub_tool_inner.h" |
| #if defined(ENABLE_INNER_CLIENT_REQUEST) |
| #include "helgrind/helgrind.h" |
| #endif |
| #include "priv_sema.h" |
| |
| /* |
| Slower (than the removed futex-based sema scheme) but more portable |
| pipe-based token passing scheme. |
| */ |
| |
| /* Cycle the char passed through the pipe through 'A' .. 'Z' to make |
| it easier to make sense of strace/truss output - makes it possible |
| to see more clearly the change of ownership of the lock. Need to |
| be careful to reinitialise it at fork() time. */ |
| static HChar sema_char = '!'; /* will cause assertion failures if used |
| before sema_init */ |
| |
| void ML_(sema_init)(vg_sema_t *sema) |
| { |
| HChar buf[2]; |
| Int res, r; |
| r = VG_(pipe)(sema->pipe); |
| vg_assert(r == 0); |
| |
| vg_assert(sema->pipe[0] != sema->pipe[1]); |
| |
| sema->pipe[0] = VG_(safe_fd)(sema->pipe[0]); |
| sema->pipe[1] = VG_(safe_fd)(sema->pipe[1]); |
| |
| if (0) |
| VG_(debugLog)(0,"zz","sema_init: %d %d\n", sema->pipe[0], |
| sema->pipe[1]); |
| vg_assert(sema->pipe[0] != sema->pipe[1]); |
| |
| sema->owner_lwpid = -1; |
| |
| /* create initial token */ |
| sema_char = 'A'; |
| buf[0] = sema_char; |
| buf[1] = 0; |
| sema_char++; |
| INNER_REQUEST(ANNOTATE_RWLOCK_CREATE(sema)); |
| INNER_REQUEST(ANNOTATE_BENIGN_RACE_SIZED(&sema->owner_lwpid, |
| sizeof(sema->owner_lwpid), "")); |
| res = VG_(write)(sema->pipe[1], buf, 1); |
| vg_assert(res == 1); |
| } |
| |
| void ML_(sema_deinit)(vg_sema_t *sema) |
| { |
| vg_assert(sema->owner_lwpid != -1); /* must be initialised */ |
| vg_assert(sema->pipe[0] != sema->pipe[1]); |
| INNER_REQUEST(ANNOTATE_RWLOCK_DESTROY(sema)); |
| VG_(close)(sema->pipe[0]); |
| VG_(close)(sema->pipe[1]); |
| sema->pipe[0] = sema->pipe[1] = -1; |
| sema->owner_lwpid = -1; |
| } |
| |
| /* get a token */ |
| void ML_(sema_down)( vg_sema_t *sema, Bool as_LL ) |
| { |
| HChar buf[2]; |
| Int ret; |
| Int lwpid = VG_(gettid)(); |
| |
| vg_assert(sema->owner_lwpid != lwpid); /* can't have it already */ |
| vg_assert(sema->pipe[0] != sema->pipe[1]); |
| |
| again: |
| buf[0] = buf[1] = 0; |
| ret = VG_(read)(sema->pipe[0], buf, 1); |
| INNER_REQUEST(ANNOTATE_RWLOCK_ACQUIRED(sema, /*is_w*/1)); |
| |
| if (ret != 1) |
| VG_(debugLog)(0, "scheduler", |
| "VG_(sema_down): read returned %d\n", ret); |
| |
| if (ret == -VKI_EINTR) |
| goto again; |
| |
| vg_assert(ret == 1); /* should get exactly 1 token */ |
| vg_assert(buf[0] >= 'A' && buf[0] <= 'Z'); |
| vg_assert(buf[1] == 0); |
| |
| if (sema_char == 'Z') sema_char = 'A'; else sema_char++; |
| |
| sema->owner_lwpid = lwpid; |
| sema->held_as_LL = as_LL; |
| } |
| |
| /* put token back */ |
| void ML_(sema_up)( vg_sema_t *sema, Bool as_LL ) |
| { |
| Int ret; |
| HChar buf[2]; |
| vg_assert(as_LL == sema->held_as_LL); |
| buf[0] = sema_char; |
| buf[1] = 0; |
| vg_assert(sema->owner_lwpid != -1); /* must be initialised */ |
| vg_assert(sema->pipe[0] != sema->pipe[1]); |
| vg_assert(sema->owner_lwpid == VG_(gettid)()); /* must have it */ |
| |
| sema->owner_lwpid = 0; |
| |
| INNER_REQUEST(ANNOTATE_RWLOCK_RELEASED(sema, /*is_w*/1)); |
| ret = VG_(write)(sema->pipe[1], buf, 1); |
| |
| if (ret != 1) |
| VG_(debugLog)(0, "scheduler", |
| "VG_(sema_up):write returned %d\n", ret); |
| |
| vg_assert(ret == 1); |
| } |
| |
| /*--------------------------------------------------------------------*/ |
| /*--- end ---*/ |
| /*--------------------------------------------------------------------*/ |
| |
| |